Method for manufacturing a network of microlenses at the ends of a bundle of optical fibres, related optical fibres and related use

Abstract

The present disclosure relates to a method for manufacturing end microlenses of individual optical fibers which are part of a bundle or a multi-core fiber, including depositing a drop of a photopolymerizable solution on a first end of the bundle; adapting the size of the drop; applying light centered on a predetermined wavelength onto a second end of the bundle in order to selectively polymerize the drop; rinsing the first end using a methanol solution in order to obtain a network of individual optical fibers, each one of which is provided with a microlens at the first end of the multi-core fiber, the microlenses being physically separated from one another. The disclosure additionally relates to a bundle of microlensed fibers obtained by the method, as well as to the use of such a bundle, for example in medical or multiplexed imaging and/or in the coupling of optical fibers.

What is claimed is: 
     
       1. A method of manufacturing microlenses at the ends of unit optical fibres forming part of a multicore fibre, comprising:
 depositing a drop of photopolymerisable solution on a first end of the multicore fibre; 
 adapting a size of the drop; 
 illuminating a light source centred on a given wavelength at a second end of the multicore fibre such that the drop is selectively polymerized; and 
 rinsing the first end with a solvent solution in order to obtain a network of unit optical fibres, each unit optical fibre provided with a microlens at the first end of the multicore fibre, wherein the microlenses are configured to physically separate from one another. 
 
     
     
       2. The method according to  claim 1 , further comprising adapting a height of the drop according to its composition so that the height is less than a distance measured substantially along a longitudinal axis of the multicore fibre, between the first end and a proximal surface containing intersections of light beams issuing from each unit optical fibre. 
     
     
       3. The method according to  claim 1 , wherein the adaptation of the size of the drop includes a reduction of its thickness to approximately a few micrometers. 
     
     
       4. The method according to  claim 1 , wherein the adaptation of the size of the drop comprises a reduction in angle A between an end plane of the multicore fibre and a plane of a tangent to the drop at a periphery, to a value of less than about 10°. 
     
     
       5. The method according to  claim 1 , wherein the photopolymerisable solution comprises a photopolymerisable monomer; an agent of a methyldiethanolamine type; and a photoinitiator agent of an eosin type. 
     
     
       6. The method according to  claim 1 , wherein the photopolymerisable solution is a radical photopolymerisable solution having a given photopolymerisation threshold, the radical photopolymerisable solution being sensitive to and induced by an inhibitor. 
     
     
       7. The method according to  claim 1 , wherein the light source has a wavelength of about 0.532 micrometers. 
     
     
       8. The method according to  claim 7 , wherein the second end is illuminated for a period of about one second. 
     
     
       9. The method according to  claim 1 , wherein the adaptation of the size of the drop includes placing the flat end of an external element of a fibre type having substantially the same outside diameter as the drop in contact with a distal curved end of the drop adhering to the first end of the multicore fibre; moving the ends away once the flat end has been loaded with a quantity of photopolymerisable solution; measuring the thickness and/or the angle A of the drop on the first end of the multicore fibre; and then, according to a result of the measurement, once again bringing the two ends closer together after any trace of solution has been removed from the flat end of the external element. 
     
     
       10. The method according to  claim 1 , further comprising obtaining a bundle of unit optical fibres including all or some of the fibres provided at one end with the microlens. 
     
     
       11. The method according to  claim 10 , wherein the bundle of optical fibres are utilized in medical or multiplexed imaging and/or in optical fibre coupling. 
     
     
       12. The method according to  claim 5 , wherein the photopolymerisable monomer is a PETIA type monomer. 
     
     
       13. The method according to  claim 12 , comprising about 4% by weight of the methyldiethanolamine type agent, and about 0.5% by weight of the eosin type photoinitiator agent. 
     
     
       14. The method according to  claim 6 , wherein the inhibitor is selected from the group consisting of oxygen, 4-methoxyphenol, and combinations thereof.